The association said inhaling ozone is comparable to a sunburn on the lung and can shorten life and trigger asthma attacks.

The State of the Air report used data from the Environmental Protection Agency, the ALA said.

It said that while air quality improved in many places, nearly 40 percent of Americans live in cities or counties with unhealthy ozone or particle pollution. Particle pollution comes from particles that arise from wildfires, coal burning plants, diesel engines or wood burning devices.

While there were air quality improvements in certain cities, Connecticut was not on the list for cleanest air cities. In fact, nearly all of its counties received an "F" grade. Windham County was the only exception with a grade of "D." See the list of grades here.

The lung association said the report underscores the importance of the Clean Air Act and urges President Donald Trump and the Environmental Protection Agency administrator to fund the act.